External tourniquet systems have long been used to establish hemostasis in the upper and lower limb in order to facilitate orthopedic surgical procedures. External tourniquet systems of the prior art typically include a pneumatic tourniquet cuff applied around a patient's limb proximal to a desired surgical field, and an external tourniquet instrument for supplying the cuff with gas at a pressure above the minimum pressure needed to stop arterial bloodflow past the cuff and into the surgical field for the duration of a surgical procedure. In this way, an external tourniquet system establishes a bloodless and clear surgical field in the limb distal to the cuff, allowing complex orthopedic surgical procedures to be performed with improved accuracy, safety and speed. Many types of external tourniquet systems have been described in the prior art, such as those described by McEwen in U.S. Pat. No. 4,469,099, U.S. Pat. No. 4,479,494, U.S. Pat. No. 5,439,477 and McEwen and Jameson in U.S. Pat. No. 5,556,415 and U.S. Pat. No. 5,855,589. However, in addition to establishing a bloodless surgical field, external tourniquet systems of the prior art also stop bloodflow to non-surgical regions of the limb, resulting in ischemia and a risk of injury to these non-surgical regions that increases as the duration of ischemia increases. Further, external tourniquet systems of the prior art apply pressure to underlying muscle, blood vessels and nerves proximal to the surgical site, resulting in a risk of injury to these tissues that increases as the level of pressure and duration of pressure application increases. In addition, anatomical considerations in certain surgical procedures, such as in hip and shoulder surgeries, may limit or completely prevent the use of external tourniquet systems for establishing hemostasis.
If an external tourniquet system is not used, then other apparatus known in the prior art may be employed to improve visualization and reduce bleeding, especially for arthroscopic surgical procedures. Some prior-art apparatus manage the flow of sterile fluid into and out of a capsule that envelops a joint, thereby to help establish a pressure within the capsule that may reduce bleeding and improve visualization, and to help remove surgical debris and blood that may be present in the capsule. Prior-art fluid management systems for arthroscopic surgery are described, for example, by Chandler et al. in U.S. Pat. No. 5,800,383, by Beiser et al. in U.S. Pat. No. 5,840,060 and U.S. Pat. No. 5,662,611. Arthroscopic fluid management systems known in the prior art require significant manual intervention, knowledge, skill and attention by the surgeon throughout a surgical procedure in order to balance a number of competing requirements: the control of bleeding in the surgical field, the minimization of extravasation or swelling of tissues surrounding the surgical field and its associated risk of patient injury; the removal of blood and surgical debris from the surgical field; the maintenance of acceptable visualization; and the minimization of fluid loss and its related costs and hazards.
To facilitate new orthopedic surgical procedures that are becoming less invasive, as well as to facilitate arthroscopic surgical procedures that are becoming increasingly complex, there is a need for an internal tourniquet that can establish adequate hemostasis and provide a sufficiently bloodless surgical field over a time period suitably long for the performance of a surgical procedure without the limitations in performance and without the risks of patient injuries associated with prior-art external tourniquet systems and arthroscopic fluid management systems.